Functional Response of a Near-Surface Soil Microbial Community to a Simulated Underground CO(2) Storage Leak

Understanding the impacts of leaks from geologic carbon sequestration, also known as carbon capture and storage, is key to developing effective strategies for carbon dioxide (CO(2)) emissions management and mitigation of potential negative effects. Here, we provide the first report on the potential effects of leaks from carbon capture and storage sites on microbial functional groups in surface and near-surface soils. Using a simulated subsurface CO(2) storage leak scenario, we demonstrate how CO(2) flow upward through the soil column altered both the abundance (DNA) and activity (mRNA) of microbial functional groups mediating carbon and nitrogen transformations. These microbial responses were found to be seasonally dependent and correlated to shifts in atmospheric conditions. While both DNA and mRNA levels were affected by elevated CO(2), they did not react equally, suggesting two separate mechanisms for soil microbial community response to high CO(2) levels. The results did not always agree with previous studies on elevated atmospheric (rather than subsurface) CO(2) using FACE (Free-Air CO(2) Enrichment) systems, suggesting that microbial community response to CO(2) seepage from the subsurface might differ from its response to atmospheric CO(2) increases.